Hi, I just signed up. I need help with the circuit layout of a 7 segment LED that would count to 99 in intervals of 1/2. Basically, what I am trying to do is attach a photoresistor to the counter. And I am going to shin a light beam to the photoresistor. Whenever, the light is blocked, the resistance increases. Hence, a count of 0.5. Please, if anyone can get me started..its really urgent. Thanks in advance.

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Digital counters only go by units, so counting by 1/2 is just not possible. You can say that a beam has to be interrupted twice to complete a function, but each event is complete in itself.

Do you have any components selected, or is this a complete circuit you want?

Do you have any components selected, or is this a complete circuit you want?

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Hi, I haven't selected any components other than a photo resistor. A complete circuit is what I need help with. If you could list the hardware/material I need, it would be great so that I could go out and buy it. Then I believe its simply putting it together. Oh, and I do need help if there is going to be any programming. Thank you for your time.

Take a look at ONsemi's datasheet for an MC14553B, which is a 4000-series 4553 3-digit BCD counter. When interfaced with a 4543 7-segment driver/latch, it can drive up to three 7-segment displays with just a few external components.

Your trick is to just use the first 2 output displays, and implement the logic for when the 3rd digit comes up with a 1 for the 1's place (Q0) and DS3\ is low, you reset the counters.

We don't typically provide complete projects for people. We help with ideas and give tips along the way. That way you actually learn something.